Meg's Mirrors

zig

1	const std = @import("std");
2	const popcount = @import("popcount.zig");
3	const testing = std.testing;
4
5	fn popcountti2Naive(a: i128) i32 {
6	var x = a;
7	var r: i32 = 0;
8	while (x != 0) : (x = @as(i128, @bitCast(@as(u128, @bitCast(x)) >> 1))) {
9	r += @as(i32, @intCast(x & 1));
10	}
11	return r;
12	}
13
14	fn test__popcountti2(a: i128) !void {
15	const x = popcount.__popcountti2(a);
16	const expected = popcountti2Naive(a);
17	try testing.expectEqual(expected, x);
18	}
19
20	test "popcountti2" {
21	try test__popcountti2(0);
22	try test__popcountti2(1);
23	try test__popcountti2(2);
24	try test__popcountti2(@as(i128, @bitCast(@as(u128, 0xffffffff_ffffffff_ffffffff_fffffffd))));
25	try test__popcountti2(@as(i128, @bitCast(@as(u128, 0xffffffff_ffffffff_ffffffff_fffffffe))));
26	try test__popcountti2(@as(i128, @bitCast(@as(u128, 0xffffffff_ffffffff_ffffffff_ffffffff))));
27
28	const RndGen = std.Random.DefaultPrng;
29	var rnd = RndGen.init(42);
30	var i: u32 = 0;
31	while (i < 10_000) : (i += 1) {
32	const rand_num = rnd.random().int(i128);
33	try test__popcountti2(rand_num);
34	}
35	}